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<p class="MsoNormal"><span style="color:#1F497D">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">When testing high load scenarios, e.g. issuing 100 volume attachments, we are running into timeout problems between nova, cinder and the centralized storage backend.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Has anybody experienced similar problems?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">/Tobi<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><a href="https://blueprints.launchpad.net/nova/+spec/volume-status-polling">https://blueprints.launchpad.net/nova/+spec/volume-status-polling</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><a href="https://blueprints.launchpad.net/cinder/+spec/volume-status-polling">https://blueprints.launchpad.net/cinder/+spec/volume-status-polling</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Tobias Engelbert [mailto:tobias.engelbert@ericsson.com]
<br>
<b>Sent:</b> Monday, November 03, 2014 11:33 PM<br>
<b>To:</b> openstack-dev@lists.openstack.org<br>
<b>Subject:</b> [openstack-dev] [cinder][nova] Timeout problems<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal">Parallel volume operations lead to inconsistencies between the OpenStack database and the deployed view on a centralized storage backend.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When performing multiple volume operation on a centralized storage backend it can come to timeouts on the OpenStack side. These timeouts can be the RPC timeout or e.g. in high availability scenarios, the HA proxy timeout.<o:p></o:p></p>
<p class="MsoNormal">When nova wants to attach a volume, it triggers the status change from available to attaching and sends initialize_connection via cinderclient to cinder API via the REST API. Cinder API performs a synchronous CALL to cinder volume, then
via the driver the centralized storage backend is contacted. When now a timeout occurs, nova triggers the database to change the volume status from attaching to available. Meanwhile the centralized storage backend performs, what was originally requested. Here
we can have a mismatch between database and the real view of the centralized storage backend.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would be curious if this behavior is also seen by others and would like to discuss possible solution.<o:p></o:p></p>
<p class="MsoNormal">/Tobi<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">See also<o:p></o:p></p>
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<p class="MsoNormal"><span class="pln"><span style="color:black"><a href="https://blueprints.launchpad.net/cinder/+spec/volume-status-polling">https://blueprints.launchpad.net/cinder/+spec/volume-status-polling</a></span></span><span class="com"><span style="color:black">
</span></span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:black"><a href="javascript:;">11</a></span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><a href="https://review.openstack.org/#/c/132225/">https://review.openstack.org/#/c/132225/</a><o:p></o:p></p>
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